Coffee beans are generally roasted, milled, and brewed with hot water to produce a beverage that is valued for its flavor and aroma characteristics as well as for its caffeine content, the latter of which helps the coffee drinker remain awake and alert. Flavor, aroma and color are developed in coffee beans in the course of a roasting process at temperatures typically exceeding 230 degrees Celsius (approximately 450 degrees Fahrenheit). The least (lightest) roasted coffee is generally considered to be the so-called “cinnamon roast” in which the coffee bean is exposed to a temperature of approximately 390° F. and where the internal temperature of the beans reaches approximately 196° C. (385° F.). It is understood that to be considered cinnamon roasted coffee, the bean temperature should not reach 400° F. A complex group of chemical reactions involving proteins and carbohydrates occur during roasting. These reactions are largely responsible for flavor and color development, and are known as the Maillard reactions.
While roasted coffee beans are occasionally consumed in a food or beverage, e.g., incorporated as whole beans into chocolate candies or powdered and imbibed in Turkish coffees, green coffee beans are not generally eaten. That is because green coffee beans are too tough to be masticated, and even when milled into small particles, green coffee beans have a somewhat unpleasant and raw bean-like flavor. Nevertheless, Vella et al., in Published U.S. Pat. Appl. No. 2011/0305792A1, suggest that milled green coffee beans can be ingested, primarily as a dietary supplement. Green coffee beans naturally contain high levels of a group of water-soluble phenolic antioxidants known as chlorogenic acids (collectively abbreviated “CGA”). The CGA antioxidants are believed to provide significant health benefits when consumed on a regular basis. CGA antioxidant levels in green coffee beans typically range between approximately 5% and 10% by weight of the beans. Coffee beans of the species Coffea robusta generally contain somewhat higher levels of CGA than beans of the species Coffea arabica. As many as nine or more different molecular isomers of CGA constitute a family of antioxidants (Moon et al., J. Agric. Food Chem. 2009, 57, 5365-5369). The principal members of this family include the caffeoylquinic acids, dicaffeoylquinic acids and feruloylquinic acids. CGA antioxidants are nearly quantitatively released from milled coffee beans during the brewing of coffee with hot water. However, roasting of coffee beans is known to degrade CGA.
To preserve and provide higher CGA levels to the consumer, Vella et al., in Published U.S. Pat. Appl. No. 2011/0305792A1 describe a method of processing green coffee beans that avoids significant heating of the beans. Methods for cold-sterilizing, low temperature drying, grinding, stabilizing and packaging green coffee beans as a dietary supplement or food additive are described. Exposure of the product to temperatures exceeding 130° F. (54° C.) for more than a few seconds is avoided, although 12-24 hours of drying at 120° F. is recommended. The resulting milled raw coffee beans are provided as a nutritional supplement in the form of tablets, capsules or as a bulk powder, or as a food additive.
Modified heat treatments that avoid roasting have been devised for preparing improved antioxidant extracts from coffee beans. For example, Leloup et al., in Published U.S. Pat. Appl. No. 2012/0251678A1 describe the importance of avoiding traditional roasting or any other dry heat treatment of green coffee beans or extract. Accordingly, using water and/or steam, Leloup et al. maintain a significant level of moisture, i.e., between 6% and 50% by weight of the beans, and generally cook the coffee beans. Pressure is used to cook the beans at elevated temperatures, e.g., above 100° C. Moist heat processing is understood to preserve CGA levels while allowing subsequent liquid extraction of CGA from the beans without also extracting native proteins having undesirable allergenic properties. The resulting extracts can be used in the preparation of a food or beverage product rich in CGA.
Leloup et al., in Published U.S. Pat. Appl. No. 2008/0113077A1 describe a coffee product that provides a desirable coffee flavor with an increased level of CGA in which the coffee includes 1%-90% by weight unroasted coffee and 99%-10% by weight roasted coffee. The overall CGA content in the mixed coffee product is at least 4% by weight. By comparison, it is indicated that the CGA content of green coffee is reduced as much as about 40-90% during conventional roasting.
Milo et al., in U.S. Pat. No. 8,455,019 describe a food or beverage composition that includes water-soluble coffee solids, including at least 2% arabinogalactans. At least 92% of the coffee solids are unroasted coffee solids. The solids may contain between 12% and 35% CGA. Coffee roasting that is to be avoided is described as dry or almost dry heating of coffee solids or raw green coffee beans before or after their grinding and extraction. The unroasted coffee solids as described by Milo et al., were not subjected to heat treatment at a temperature above 100° C. and a moisture level below 30% by weight. Instead, Milo's unroasted coffee solids are obtained by extraction of green coffee beans in water under pressure, preferably at a temperature above 130° C., 140° C. or even above 150° C.